William c



UNITED STATEs PATENT T FFICE.

\VILLIAM C. MURDOCK, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR TO THE NATIONAL VULCANITE COMPANY, OF NEIV YORK, N. Y.

VULCANITE PAVEMENT.

SPECIFICATION forming part of Letters Patent No. 408,250, dated August 6, 1889.

Original application filed May 16, 1888, Serial No. 274,093. Divided and this application filed November 5, 1888. Serial No. 290,038. (No specimens.)

have invented certain new and useful Improvements in Vulcanite Pavements; and I do hereby declare the following to be a full, clear, and exact description of the same.

This invention relates to the preparation and combination of materials to form whatis known as vulcanite pavement, a composition employed for paving streets, sidewalks, cellars, stables, &c.; and it consists in the novel and improved compositions and mode of treatment of the materials forming part thereof, as hereinafer described, and pointed out in the claim.

In the preparation of asphalt pavements it has heretofore been customary to prepare the asphalt by subjecting crude Trinidad asphalt in kettles or retorts to a fire heat of from 700 to 1,000 Fahrenheit, for the purpose of melting the mass to precipitate the earthy and other matters contained therein and driving off moisture. To the melted asphalt petroleum residuum is added in the proportion of about one part residuum to six parts asphalt, and the whole, being subjected to heat and agitation, produces what is known as petroleum asphalt cement.

By reason of the high degree of heat heretofore deemed necessary in carrying out this process the heavier essential oils are driven off, to the detriment of the compound and injury of the pavement made therefrom, as the heavy hydrocarbons which are necessarily expelled, instead of being detrimental, are exceedingly valuable in maintaining the life and tenacity of the matrix, and their removal renders the residuum brittle, more liable to be injured by exposure to the atmospheric influences, as well as being more friable, and thus more readily destroyed and worn away when subjected to heavy or constant traffic, as in large cities. To counteract or in a measure compensate for the loss of the oils driven off in the preparation of the asphalt, petroleum residuum is added; but this again, being subjected to the high heat, is in turn deprived of a large portion of its more volajtile oils.

Hence it sometimes becomes nodes sary or advisable to add in the subsequent treatment a certain proportion of petroleum residuum. As is well known, petroleum and petroleum residuum contain active solvents of bituminous matter, and their effect upon the 5 5 asphalt, especially when the former contains the lighter oils, is of such a nature as to render it extremely diflicult and practically impossible to thoroughly unite the asphalt cement with artificial asphalts made from coal- 6o tar or such as contain these artificial asphalts in large proportions.

As the result of much experieneeand many trials I have discovered that it is possible to avoid or counteract these defects both as to the manufacture and product by substituting coal-tar residuum for petroleum residuum and subjecting the crude asphalt to a temperature not exceeding 500 Fahrenheit. In

practicing this part of my invention I place the crude natural asphalt in a retort or other vessel and add the coal-tar distillatei. 8., coal-tar deprived of the lighter oils-in about the proportion of seven parts of the former to one of the latter, and heat the mixture to a temperature of 450 Fahrenheit, retaining it at or about this temperature, but never exceeding 500 Fahrenheit,until the asphalt has been completely melted or amalgamated with the coal-tar distillate. In this way I manage to preserve all the desirable qualities and constituents of both the asphalt and coal-tar, while eliminating the lighter oils, or such as in practice have been found deleterious or destructive to the life of the pavement, at the same time effecting a eomplete admixture of the two substances. The addition of the coal-tar distillate to the asphalt also assists materially in expediting the liquefaction and solution of the asphalt when subjected to the relatively low temperature employed. The mixture is maintained at a practically-uniform temperature of 450 Fahrenheit until evaporation ceases, and it is then in condition to readily and naturally combine with most, if not all, of the bituminous compounds such as are employed for paving and similar purposes.

quired wearing-surface.

To form my improved paving compound or mixture, the asphalt thus produced is united with distillate of coal-tar which has been previously subjected to a temperature not ex ceeding 450 Fahrenheit to drive off the more volatile oils, the proportions employed being approximately seventy parts of the distillate to thirty parts of the asphalt, forming an asphalt cement possessing uniform properties and retaining all the heavier hydrocarbon oils and compounds not evaporating at the temperature to which the materials have been SUbj6Ct6(l--t. 6., 450 Fahrenheit. Having thus produced my asphaltic cement, I proceed to prepare the ingredients, which, when combined therewith in-the manner and proportions specified, constitute the paving mate rial. These materials oringredients are clean, fine, and sharp sand, carbonate of lime, sulphur, sulphate of calcium, mineral wool or asbestus,hydraulic cement, calcareous gravel, and stone-dust in proportions varying with the climate and service to which the pave: ment is to be subjected, the proportions also varying somewhat according to the relative coarseness or fineness of the materials used. Thus to form the wearing-surface I may employ seventy parts sand, one part hydraulic cement, ten parts gravel, one part sulphur, six parts carbonate of lime, six parts sulphate of calcium, two parts mineral wool or asbestus, and six parts stone-dust. These ingredients are thoroughly mixed and heated to a temperature not exceeding 250 Fahrenheit, but preferably at 230 Fahrenheit, and to this heated mixture I add at the same temperature a sufficient quantity of the asphaltic cement, prepared as described, to form the re- The quantity of asphaltic cement will necessarily vary somewhat with the climate and thickness of the wearing-surface of the pavement; but it is usually within a margin of from five to eight per cent. of asphalt cement to one hundred per cent. of the metal described. The materials-asphaltic cement and metal-are placed in an amalgamator and thoroughly mixed, after which, and while still hot. and plastic, they are taken to the locality where the pavement is to be laid and spread upon a prepared surface raked to the proper degree of thickness and tramped and rolled into a solid homogeneous mass or coating. The surface is then covered with hydraulic cement, or preferably a mixture of hydraulic cement and sulphate of calcium in about equal proportions, after which it is rolled again until cold and fit for use.

For street-work I prepare the base or substratum by first leveling off the surface to the proper grade and placing thereon a layer of brok'en stone, the larger stone being placed at the bottom and the smaller on top. This mass of stone is then covered and the interstices filled with coal-tar distillate and rolled into a solid mass or layer of the required thickness. Upon the base thus formed is spread the binder course, consisting of small stone previously heated to about 150 Fahrenheit and mixed with the prepared asphaltic cement hereinbefore described in the proportion of about one gallon of asphaltic cement to one cubic foot of metal. This mixture is laid evenly upon the prepared substratum and rolled to the required thickness, after which the wearing-surface is applied in the manner previously explained.

By preparing the binder course with the asphaltic cement and interposing it between the coal-tar distillate of the substratum and the asphaltic cement of the upper or wearing face a more perfect amalgamation of the several courses is effected, and the life and endurance of the wearing-surface, the part most subject to decay, is increased and prolonged.

Ido not claim herein the improved process of preparing the paving compound or asphaltic cement, the same forming the sub ect of my prior application, Serial No. 274,093, of which this is a division.

I am aware that it is not new to employ a mixture of asphalt and petroleum residuum in the several courses or layers of a pavement, as described in Patent No. 188,614, granted to L. S. Filbert March 20, 1877; but my present invention differs therefrom both in the manner of treating the materials and the use of coal-tar distillate in place of petroleum residuum, which latter is open to all the objectionable features hereinbefore pointed out. I am also aware that it is not new to form a pavement in three or more courses or layers the materials whereof are united by mixtures of bitumen and oil or bitumen and asphalt, as described in the patent to Scharf, No. 111,151, dated January 24:, 1871, and I do not claim the same. My invention constitutes, in effect, an improvement upon both the Filbert and Scharf processes, in that the asphalts are reduced at a much lower temperature by the employment of coal-tar residuum, the latter being maintained of substantially the same density both in the base, where it is alone employed, and in the upper courses, where it is mixed with asphalt, the result being the production of a substantially-homogeneous pavement, the coal-tar distillate employed in each course or layer having been subjected to substantially the same degree of temperature.

Having thus describedmy invention, what I claim as new is The hereinbefore-described improvement in the art of forming and laying vulcanite pavements, which consists in first preparing a base or substratum of broken stone, filling the interstices with coal-tar distillate, and rolling; secondly, preparing a binder course of smaller stone heated and thoroughly mixed with asphaltic cement prepared by subjecting asphalt and coal-tar distillate to a temperature of about 450 Fahrenheit and not exceeding 500 Fahrenheit, laying said binder course evenly upon the base, and rolling, and,

finally, applying and rolling; a top coating or thereto dry hydraulic cement and powdered surface prepared by mixing comminutecl minsulphate of calcium, substantially as set forth. eral substances of which one in 'redient is sulphur, With asphalt and coal-tar previously VILLIAM MURDOOK 5 subjected to a temperature of about 450 Witnesses:

Fahrenheit, but less than 500 Fahrenheit, S. H. STEVENS,

and protecting the top surface by applying GEORGE O. HI TT.

It is hereby certified that in Letters Patent No. 408,250, granted August 6, 1889,

upon the application of William O. Murdock, of Washington, District of Columbia, for an improvement in Vnloanite Pavements, the name and residence of the assignee is erroneously Written and printed National Vuloanite Company, of New York, N. Y.,

Whereas it should be National Vnlcanr'te Company of New Jersey and doing business in New York, N. 1 and the Letters Patent should be read with this correction therein to conform to the record of assignments in this office.

Signed, conntersigned, and sealed this 13th day of August, A. D. 1869.

GEO. CHANDLER,

Acting Secretary of the Interior. Oountersigned ROBERT J. Frsnnn,

Acting Commissioner of Patents. 

